Validated, simple, rapid and sensitive spectrophotometric and spectrofluorimetric methods were developed for the determination of dapoxetine HCl and dosulepin HCl. The spectrophotometric method (I) was based on a binary complex formation between each drug and mercurochrome (MER) in acetate buffer (pH 3.5) with maximum absorbance at 557 nm. Calibration graphs were linear over the range 2.0–20.0 and 2.0–24.0 μg/ml, detection limits were 0.23 and 0.41 μg/ml and quantitation limits were 0.71 and 1.26 μg/ml for dapoxetine HCl and dosulepin HCl, respectively. Spectrofluorimetric method (II) was based on the measurement of the quantitative quenching effect of each drug on the native fluorescence of MER at the same pH. Fluorescence quenching of MER was measured at 538 nm after excitation at 470 nm. Calibration graphs were linear over the range 0.5–10.0 and 0.4–10.0 μg/ml, detection limits were 0.17 and 0.12 μg/ml and quantitation limits were 0.5 and 0.36 μg/ml for dapoxetine HCl and dosulepin HCl, respectively. Statistical comparison of results with those obtained by reported methods provided good agreement and revealed that there were no significant differences in accuracy and precision between methods. The proposed methods were applied successfully to analyse commercial tablets and capsules containing the studied drugs.

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A facile, accurate, eco-friendly and sensitive spectrofluorometric method was evolved to assay alfuzosin hydrochloride (AFH) and tadalafil (TDF) in different matrices. Such a co-administered combination is clinically used for the treatment of lower urinary tract symptoms. Both compounds are characterized by their native fluorescence spectra upon excitation at specific wavelengths. Their characteristic fluorescence spectra were used for sensitive assay of the studied analytes in tablets and human biological samples. The assay principle is based on first-order synchronous spectrofluorometric scan using Δ λ = 60 nm in which AFH peaks were recorded at 366 nm. Meanwhile, TDF measurements were recorded at 293 nm in the same scans without overlap with AFH spectra. Recent analytical chemistry trends were implemented to lessen occupational and environmental perils, using ethanol as a diluting solvent for method optimization and application. Linearity ranges were 5.0–90.0 and 10.0–100.0 ng ml −1 for AFH and TDF, respectively in their raw materials with average % recoveries of 100.44% and 99.73% in raw materials, 100.15% and 100.20% in spiked plasma, and 97.14% and 99.99% in spiked urine. The proposed method was successfully applied to Prostetrol and Starkoprex commercial tablets with no interference with common tablet additives.

COVID-19 is a fast-spreading pandemic that is caused by SARS-CoV-2 viral pathogen. Combination therapy of the antiviral favipiravir and the anticoagulant apixaban is one of the efficient treatment regimens. Therefore, development of novel and sensitive methods for simultaneous analysis of such combination is highly advantageous. Herein, two eco-friendly, simple, rapid, and cost-effective spectrofluorometric methods were evolved for the estimation of favipiravir and apixaban in pharmaceutical and biological matrices. Method I was based on analysis of favipiravir and apixaban by the first-order derivative of the conventional fluorescence spectra obtained after excitation at 300 nm, where favipiravir and apixaban were detected at 468.8 and 432.0 nm, respectively. Method II relied on dual scan synchronous spectrofluorometry, in which favipiravir was determined at 364 nm using Δλ = 60 nm while apixaban was analyzed at 274 nm using Δλ = 200 nm. Method optimization was performed for selecting the optimum conditions at which maximum sensitivity and selectivity were obtained. This report is the first one that describes simultaneous analysis of favipiravir and apixaban by synchronous spectrofluorometry. The developed methods were successfully applied to evaluate favipiravir and apixaban in spiked human plasma and in pharmaceutical dosages with high %recoveries and low RSD.